Switch box having plug-in outlet



Feb. 17, 1942. TORNBLQM 7 2,273,729

SWITCH BOX HAVING PLUG-IN OUTLET Filed July 31, 1940 2 Sheet-Sheet l I &

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SWITCH BOX HAVING PLUG-IN OUTLET Filed July 31, 1940 2 Sheets-Sheet 2 mag a. fw

Patented Feb. 17, 1942 Nils A. Tornblom, ole-u age;1:11;, assignor t'o Appleton Electric Company, a corporation of Illinois Application-July 31, 1940, Serial No..348,939

9 Claims. (01. 200---l"68 I The primary object of. the present invention is to produce a simple and novel switch box construction that makes it practically impossible to cause explosions due to arcing under any condition likely to be encountered in the use thereof.

In the case of switch boxes to which the incoming and outgoing conductors are permanently attached all that is needed to prevent explosive gases inthe surrounding atmosphere from igniting is effectively to seal the boxes. However, when cords or cables are intendedto be connected and disconnected to a box at will, arcing at. exposed terminals may occur and explosionsresult.

One of the objects of the present invention is toprevent arcing between the contacts of a separable connector associated with .a switch box whereby the possibility of explosions. resulting from such cause are eliminated.

Sometimes in electrical distributing systems in buildings or other structures, switch boxes are connected to conduits embedded in a wall or, at least lying .behind the wall faces at which the outlets from the boxes are to be located. Anobject of the present invention is to make itp-ossible readily to adjust the outlet of a switc'hlbox toward and away from the inlet, so as to permit the outlet to be accurate'ly'positioned with respect to a wall face, for example, regardless of the depth to which the box must extend behind such face.

The various features of novelty whereby my invention is characterized will hereinafter be pointed out with particularity'in the claims; but, fora full understanding of my invention and of its objects and advantages, reference may be hadtothe following detailed description taken in conbox proper, partly in vertical section and partly in elevation; Fig. 6 is a section on line 6--& of

Fig. Fig. 7 is a, section on line l'l of Fig. 5,

showing only a fragment of what may be termed.

the top cover member; Fig. 8 is view partly in section and partly in side elevation of the switch handle and the parts near the same; Fig. 9 is a section. on line 9-9. of Fig. 8; Fig. 10 is a view of the lower. end. of; the sleeve or shell of the plug.

member, showing. the. portion that lies oppositev the switch. handle when the plug member is engagedv with the receptacle member on the box;

1 and. Fig. L1 is asection taken approximately in line lit-l l of. Fig. 7.

Referring to the drawings, 1'. represents a box which. may be anoutlet box or connector box of any desired size and: shape- The top wall ot the: box contains a round opening giving freeaccess to the interior. The metal of the wall is thickened around this opening, as indicated at 2, to provide space. for a considerable number of screwthreads 3 sleeve thaving around the top a thick externalflange 5 which may be said to constitute the eiiective top of the box. By screwing the sleeve inor out, the effective depth of the box may be varied through a considerable range; the considerable number of screw threads that are engaged with each other afiording an explosion.

proof jointbetween the box proper and its ex-. tension. Therefore the top face of the box'may be adjusted to bring it into the desired planewithcutmaking it necessary that a conduit to which the box is attached lie at a given distance from that plane. The sleeve may have at its lower end; one ormore ears, as indicated at 6 and I, for receiving screws, such as 8 and 9, to prevent unauthorized turning of the sleeve or its removal fromthe box after the cover has been applied.

- The cover of the boxcomprises two members, a member Hiadapted to rest on the flange 5 and a member H which rests on the member ll In the arrangement shown, the members Ill and I l'are held together and to the flange 5 by screws H. The engaging surfaces between the several parts are made wide enough to create explosion proof joints when tightly held together by the over'a considerable area to form a deep well I4.

that extends, down into the box when the cover is on, but leaves ample room in the'box for the ends of wires coming into and leading from the box. The body portion of the member in is preferably thick so that it may be recessed, from above, around the well and provide a long, wide, shallow chamber lEi into which the top of the well opens. The well has therein, at one side, a deep compartment or pocket It, open at the top. Conductors l1 extend from the exterior of the well into thepocket through. a. hole inv the bottom Screwed into this opening is a wall of the well which is then filled with a sealing compound 18. There conductors end in terminals in the form of sockets l9.

Mounted on the under side of the cover member l I is a switch 20 of any usual or suitable construction, the switch being small enough to enter the well beside the terminals [9 when the two cover members are assembled one upon the other. Projecting down from the upper cover member are two contact pins 2| adapted to enter the socket IS. The outlet for the electricity is through a receptacle on the upper cover member. This receptacle comprises a tubular hub 22 rising from the center of the cover member, a filler 24 of insulating material in the hub, and sockets 25 fixed in the filler and open at their upper ends.

Cooperating with the receptacle is a plug comprising a long sleeve 26 adapted to be slipped down over the receptacle, a body 21 of insulating material fixed in the sleeve at a considerable distance inwardly from the open lower end, and contact pins 28 fixed in and projecting downwardly from the body of insulating material. When the plug is engaged with the receptacle, the sleeve surrounds the receptacle while the pins enter the sockets in the latter. The pins 28 form terminals for the conductors in a cable 29 that enters the upper end of the sleeve 26 and is there tightly gripped in a clamp 30. The cable, of course, carries the current to the point of use.

The switch is adapted to be opened and closed through the operation of a handle 3| overlying the cover member H close to the receptacle. The handle has a screw-threaded stem 32, (as in Patent No. 2,029,599) extending through the member H to provide an explosion proof pivotal connection between the handle and the cover member. On the lower end of the stem is fixed a plate 34 which as the handle is shifted from one position to another, causes the switch to open or close, as the case may be. In the arrangement shown,the immediate actuator for the switch is a little push button 35, best seen in Fig. 11. A spring finger 36 is fastened at one end to the top of the switch casing and extends in an upwardly inclined direction above the push button. This finger is in the path of the plate 34 so that, when the handle is shifted into the closed-switch position, the plate 34 presses the finger down and the latter, in turn, presses the push button down. When the handle is returned to the off switchopen position, the finger 36 springs back and allows the push button to rise and again open the switch. In order that the switch shall open and close quickly, there is connected at its ends to the plate 34 and to the cover member I I, respectively, a coiled compression spring 31 which is under maximum compression and extending radially of the handle when the handle is about midway between its on and off positions. whenever the handle is moved a little more than half way from one position to the other, the spring instantly completes the movement.

It is important that no arcing take place between the contacts in the plug and the receptacle at times when the plug is withdrawn and, also that the contacts in the receptacle be kept dead when the plug is out. To this end means are provided to lock the plug against removal while the switch is on and to lock the switch in its open position while the plug is out. The first of these results is attained by simply cutting a little transverse groove 38 in the periphery of Therefore,

the sleeve just opposite the inner end of the switch handle and providing that end of the handle with a projecting fin or web 39 that enters this groove when the handle is moved into the on position and is carried clear of the groove when the handle is moved into the off position.

The locking of the switch handle in the off or switch-open position is effected by a little pin 40 that is slidably mounted in a vertical hole M in the top of the cover member I I. When free to do so, a spring 42 in the hole 4| below the pin holds the pin up so that it projects a substantial distance above the surface of the member II. The parts are arranged so that pin 46 lies one half under the end of the switch handle and one half in the space down which the sleeve 26 travels when the plug is operatively engaged with the receptacle. As best shown in Fig. 9, the inner end of the switch lever has a notch 43 in the lower portion of its vertical face at such a point that it registers with the locking pin when the handle is in the oil position. Thus, while the switch is open and the plug is out, the pin locks the handle against movement toward the on position. However, when the plug is engaged with the receptacle, the lower edge of the sleeve 26 presses the locking pin down until its upper face is flush with the top face of the upper cover member, as shown in Fig. 5, and the switch handle is freed so that it may be shifted back and forth at will. As before explained, the plug cannot be pulled out except when the switch handle is in the off position, so that the handle must be automatically locked in the off position when the plug is withdrawn.

While I have illustrated and described with particularity only a single preferred form of my invention, I do not desire to be limited to the exact structural details thus illustrated and described; but intend to cover all forms and arrangements which come within the definitions of my invention constituting the claims.

I claim:

1. In combination, a cover for a connection box comprising two members lying one upon the other, said members being shaped to form between them a sealed switch chamber the lower portion of which extends down into a box to which the cover is applied, a switch in said chamber, contact pieces on said members engaging with each other in said chamber when said members are brought together to eifect connections in a circuit containing said switch, an outlet for said circuit including a connector adapted to be plugged into the upper cover member, and leadin wires passing through and sealed in a wall of the said lower portion of said chamber.

2. In combination, a cover for a connection box comprising two members lying one upon the other, said members being shaped to form between them a sealed switch chamber the lower portion of which extends down into a box to which the cover is applied, a switch in said chamber, contact pieces on said members engaging with each other in said chamber when said members are brought together to effect connections in a circuit containing said switch, terminals for said circuit on and accessible from the exterior of the upper cover member, and lead-in wires passing through and sealed in a wall of the said lower portion of said chamber.

3. In combination, a cover for a connection box comprising two members lying one upon appended the other, said members being shaped to form between them a sealed switch chamber the lower portion of which extends down into a box to which the cover is applied, a switch mounted on the under side of the upper cover member and housed in said chamber, contact pieces on said I members adapted to engage with each other in said chamber when said members are brought together and thereby effect connections in a circuit containing said switch, an outlet for said circuit including a connector adapted to be plugged into the upper cover member, and lead- -in wires passing through and sealed in a wall of the said lower portion of said chamber.

4. In combination, a cover for a connection box comprising two members lying one upon the other, said members being shaped to form between them a sealed switch chamber the lower portion of which extends down into a box to which the cover is applied, a switch in said chamber, contact pieces on said members engaging with each other in said chamber when said members are brought together to effect connections in a circuit containing said switch, an outlet for said circuit including a connector adapted to be plugged into the upper cover member, lead in wires passing through and sealed in a wall of the said lower portion of said chamber, means securing said members together, and means to secure the cover as a whole to the box.

5. In combination, a cover for a connection box having a large deep open-top well in the body thereof adapted to enter a box which the cover is applied to, a second cover overlying the main cover, a switch mounted on the under side of the second cover and extending into said well, cooperating contact pieces mounted in the well and on the second cover to effect circuit connections through the switch upon the placing of sealed in a wall of said well. a

6. In combination, a main cover for a connection box having a large deep open-top well in the body thereof adapted to enter a box to which the cover is applied, a second cover overlying the main cover, a switch mounted on the under side of the second cover and extending into said well, cooperating contact pieces mounted in the well and on the second cover to effect circuit connections through the switch upon the placing of the second cover on the main cover, terminals on and accessible from the exterior of the second cover, a member adapted to be attached to a cable and having terminals adapted to interengage with the aforesaid terminals and detachably secure said member to the second cover, and lead-in wires passing through'and sealed in a wall of said well.

7. In combination, a main cover for a connection box having a large deep open-top well in the body thereof adapted to enter a box to which the cover is applied, a second detachable cover overlying the main cover, a switch mounted on the under side of the secondary cover and extending into said well, cooperating contact pieces mounted in the well and on the second cover to effect circuit connections through the switch upon the placing of the second cover on the main cover, terminals on and accessible from the exterior of the second cover, said Well containing an open recess in communication with the exterior through a hole in the wall of the well, lead-in wires extending through said hole and recess into the well, and a sealing compound in the well around said wires.

8. In combination, a main cover for a connection box having a large open-top well in the body thereof adapted to enter a box to which the cover is applied, a second cover overlying the main cover, a switch mounted on the under side of the secondary cover and extending into said well,

cooperating contact pieces mounted in the well and on the secondary cover to effect circuit connections through the switch upon the placing of the second cover on the main cover, screws passing through both covers and into a part of the box to secure both covers to the box, terminals on and accessible from the exterior of the second cover, a member adapted to be attached to a cable and having terminals adapted to interengage with the aforesaid terminals and detachably secure said member to the second cover, a switch-operating element on the exterior of the second cover, and means to interlock said member and said element to prevent said member from being detached while the switch is closed and to prevent the switch from closing while said member separated from the second cover.

9. In combination, a switch box provided with a receptacle and a cooperating detachable plug,

a switch handle pivoted to the box adjacent to the receptacle, a catch on the box moveable from an idle position to a handle-locking position, a spring tending to move the handle into and hold it in the open or the closed position when the handle is carried past center in travelling toward either of said positions from the other position, said catch having a part lying in the path of the plug when the latter is engaged with the receptacle and thereby causing the catch to be shifted to its release position, and shoulders on the plug and the handle adapted to interlock and prevent withdrawal of the plug after the handle hasbeen swung into the closed-switch position.

NILS A. TORNBLOM. 

